A conductivity sensor includes a measuring circuit for measuring the electrical conductivity of a medium based upon a resistance measurement of the medium and the subsequent calculation with a factor that is referred to as a cell constant and results from the geometry of the conductivity sensor. Typically, the measuring circuits for a conductivity sensor are adjusted during the production. In the process, errors, such as amplification and zero point errors, are determined, and correction values, if any, are stored in the non-volatile memory. Such an adjustment usually occurs at room temperature, since a change in the temperature is difficult to implement during the adjustment. Such a conductivity sensor is operated at the customer's premises for a time period of many years and is there exposed to various environmental conditions, such as humidity and temperature fluctuations.
The correction values for the measuring circuit are determined at a point in time when defined environmental conditions, such as temperature, prevail. As a result of molding of the measuring circuit from, for example, epoxy resin, temperature fluctuations, or aging over a long period of operation, deviations in the measuring chain of the measuring circuit can occur. These deviations may possibly impair the specified measurement precision of the conductivity sensor.